Circular saw with improved movable guard construction

ABSTRACT

The adjustably mounted base plate carries a first abutment formation adjacent the trailing end of the slot which is formed therein to receive the circular saw blade. The lower blade guard has a second abutment formation thereon adjacent its workengaging forward end. The second abutment formation is brought into abutting engagement with the first abutment formation upon movement of the lower blade guard toward its open position whereby the lower blade guard exposes only the blade teeth which extend through the slot in the base plate irrespective of the angular disposition of the latter. A manually operated retracting mechanism for the lower blade guard includes linkage operated by a handle mounted on the side of the fixed blade guard which is adjacent the tool motor.

United States Patent [191 Kaman et al.

[ CIRCULAR SAW WITH IMPROVED MOVABLE GUARD CONSTRUCTION [75] Inventors:Frank A. Kaman, Prospect Heights; Harold McConnaughay, Batavia,

both of 111.

[73] Assignee: Skil Corporation, Chicago, Ill.

[22] Filed: Dec. 10, 1971 [21] Appl. No.: 206,639

[52] US. Cl. ..l43/159 H- [451 May 1, 1973 Primary ExaminerDonald SchranAtzorney-McDougall, Hersh & Scott 57 ABSTRACT The adjustably mountedbase plate carries a first abutment formation adjacent the trailing endof the slot which is formed therein to receive the circular saw blade.The lower blade guard has a second abutment formation thereon adjacentits work-engaging forward end. The second abutment formation is broughtinto abutting engagement with the first abutment formation upon movementof the lower blade guard toward its open position whereby the lowerblade guard exposes only the blade teeth which extend through the slotin the base. plate irrespective of the angular disposition of thelatter. A manually operated retracting mechanism for the lower bladeguard includes linkage operated by a handle mounted on the side of thefixed blade guard which is adjacent the tool motor.

5 Claims, 6 Drawing Figures Patented May 1, 1973 3,730,239

2 Sheets-Sheet 1 Patented May 1, 1973- 2 Sheets-Sheet 2 CIRCULAR SAWWITH IMPROVED MOVABLE GUARD CONSTRUCTION BACKGROUND OF THE INVENTION 1.The Field of the Invention The field of the invention relates toportable, power operated circular saws. More particularly, the inventionrelates to new and improved mechanism for the retractable lower bladeguard of such a saw.

2. The Prior Art It is known in the prior art to provide a circular sawwith an adjustable base plate. Such base plate is pivotally connected atits forward end to the saw housing for swinging movement about an axisparallel with the axis of rotation of the blade mounting shaft. The baseplate may be adjustably mounted in any desired position between aso-called normal position and a position inclined with respect thereto.A circular saw of this type has a lower or movable blade guard which, inthe closedposition thereof, cooperates with an upper or fixed bladeguard to enclose substantially all of the teeth on the circular blade.If such lower blade guard is swung to its fully open or retractedposition and if the base plate is positioned in one of its inclinedpositions, the teeth on the circular saw blade between the base plateand the blade guards will be exposed. These exposed teeth are above thework and consequently present a potentially dangerous condition to theoperator of the tool.

Circular saws of this type have been provided with manually operatedretracting mechanisms for the lower blade guard. Many of such retractingmechanisms can be operated only by placing of the users fingers in theapproximate vicinity of the saw blade, thereby presenting a hazardoussituation.

SUMMARY AND OBJECTS OF THE INVENTION A primary object of the presentinvention is the provision of a portable, power operated circular saw ofthe type described, which saw embodies new and improved safety features.

Another object of the present invention is the provision of a circularsaw of the type described having cooperating abutment means on the baseplate and lower blade guard so that irrespective of the position of thebase plate the only teeth on the circular blade which are exposed arethose extending through and beneath the slot in the base plate.

Still another object of the present invention is the provision of acircular saw of the type described having a retracting mechanism for thelower blade guard which embodies safety features, one such featureresiding in the location of the operating lever of the retractingmechanism in an area quite remote from the exposed portion of the sawblade.

These and other objects and advantages of the present invention willbecome apparent from the following specification disclosing a preferredembodiment shown in the accompanying drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a circularsaw embodying the present invention;

FIG. 2 is an enlarged side elevational view of the saw of FIG. 1, withcertain parts being broken away for better illustration of theinvention;

FIG. 3 is an enlarged, fragmentary view of the adjustment arm mounted onthe base plate, which arm inturn mounts one of the abutment formations;

FIG. 4 is a section taken along the line 4-4 of FIG. 2, all parts beingshown in broken lines except for the lower blade guard retractingmechanism;

FIG. 5 is a side elevational view of the circular saw as seen from theside opposite the side shown in FIG. 2; and

FIG. 6 is an enlarged, fragmentary perspective view of the forward endof the lower blade guard showing the other abutment formation.

DESCRIPTION OF A PREFERRED EMBODIMENT Referring to the drawings, aportable, power operated circular saw, generally designated10, whichembodies the present invention, includes a frame or housing 11 having afixed upper blade guard defined by a generally semicircular plate 12, anintegral arcuate web 13 and an integral generally semiannular flange 15.This plate, web and flange cooperate to enclose the teeth on the upperportion of a circular saw blade 16.

The frame supports the usual handle 18. The housing also defines a space19 receiving; an electric motor 20 of suitable construction, such motorincluding a shaft 21 having teeth at the outer end thereof in engagementwith the teeth on a gear 22. This gear is mounted on a ship with theblade mounting shaft 23 therebymount ing the base plate for swingingmovement back and forth between a normal position, shown in solidlinesin FIG. 2, and an inclined position shown in broken lines in thatfigure of the drawings.

The base plate 25 includes an elongated slot 28 for I receiving aportion of the circular blade l6 therethrough. The base plate alsoincludes an upstanding bracket 29 adjacent the trailing end of the slot28, which bracket is pivotally engaged, as by means of a pin 30, to anadjustment arm 31. The adjustment arm-includes an arcuate slot32slidablyreceiving the stem .of an adjustment fastener 34, suchfastener including an operating lever 35. It will be understood that thelever 35 is operated to control frictional engagement between thefastener 34 and the arm 31 thereby releasably to secure the base platein either the normal or inclined positions shown or in any selectedposition therebetween to achieve the desired depth ,of cut; As isconventional in the art, the base plate is also mounted by adjustmentmeans (not shown) for pivoting movement about its longitudinal axis toperform bevel sawmg. V

A lower blade guard, generally designated 37, includes a plate 38 havinga circular opening receiving a bearing ring 39, the latter beingconcentric with the blade mounting shaft 23 and mounting the lower bladeguard 37 for rotation about such shaft. The lower blade guard includesan arcuate web 40 integral with the plate 38 and an arcuately extendingflange 41 which in turn is integral with the web 40.

The lower blade guard 37 is illustrated in the closed position thereofin FIG. 2 with the rearward portion thereof being nested within therearward portion of the t upper blade guard. in such closed position,the lower blade guard cooperates with the upper blade guard to enclosesubstantially all of the teeth on the circular blade 16 only a few teethbetween the base plate 25 (when the same is in its normal position) andthe work engaging or forward end 42 of the lower blade guard areexposed.

An abutment formation 44 is welded or otherwise secured to theadjustment arm 31 as best illustrated in FIG. 3. Another abutmentformation 45 is integrally formed on the plate 38 of the lower bladeguard adjacent the forward end 42 of the latter. These abutmentformations are arranged such that the formation 45 will be brought intoabutting engagement with the formation 44 during movement (clockwise asseen in FIG. 2) of the lower blade guard 37 from its closed positiontoward its open or retracted position. This engagement between theabutment formations prevents furthe; movement of the lower blade guardtoward its open position.

It will be seen that irrespective of the position of the base plate, itwill be possible to retract the lower blade guard to an extent exposingonly the teeth on the circu lar saw 16 which extend through the slot 28beneath the base plate 25. Since abutting engagement of the formations44, 45 limits opening movement of the lower blade guard 37 and since theformation 44 is carried by the base plate adjacent the trailing end ofthe slot 28, it will not be possible to retract the lower blade guard toan extent such that the saw teeth above the base plate are exposed, andthis result will be obtained in all positions of the base plate.

A manually operated retracting mechanism for the lower blade guardincludes an operating lever 47 pivotally mounted to the plate 12 of theupper blade guard, as by means of a pin 48. It is noted that thisoperating lever is mounted on the side of the upper blade guard which isadjacent the housing 11 enclosing the motor 20. The distal end of thislever includes a finger engaging portion 49.

A first link 50 has one end thereof secured to the pin 48 for movementin unison with the operating lever 47. The link 50, which is disposedwithin the upper blade guard, has the other end thereof pivotallyconnected, as by means of a pin 52, to one end of another link 53. Thelink 53 has the other end thereof pivotally engaged with the lower bladeguard 37, as by means of a pin 54. A spring 55 has one end thereofengaged with the plate 38 of the lower blade guard and the other endthereof connected to the plate 12 of the upper blade guard; the spring55 acts to urge the lower blade guard 37 in a counterclockwise direction(FIG. 2) to the closed position illustrated in that figure.

It will be apparent that when the operating lever 47 is lifted, thelower blade guard is swung toward its open position until such time asthe abutment formation 45 is brought into engagement with the abutmentformation 44. As noted in FIG. 2, the lever 53 is bent intermediate theends thereof partially encircling the blade mounting shaft 23 such thatthe respective ends of this link are disposed generally above andbeneath the blade mounting shaft when the lower blade guard is in itsclosed position. This configuration of the link 53 improves themechanical advantage of the links thereby facilitating manual retractionof the lower blade guard.

A stop 56 is mounted on the plate 12 of the upper blade guard to limitmovement of the operating lever 47 and thereby prevent possible bendingor jamming of the links 50, 53 during return movement of the operatinglever 47. Since the operating lever is positioned in remote relationshipfrom the portion of the circular blade which is exposed to contact thework, there is little or no danger of the operators hand coming intoengagement with the saw teeth when operating the retracting mechanism.As is conventional in the art, a pin 57 is provided on the lower bladeguard as an alternate means for retracting the same.

We claim:

1. In a portable, power operated circular saw of the type having apowered blade mounting shaft and a frame including a fixed blade guardadapted to enclose the teeth on the upper portion of a circular blademounted on said shaft, a base plate having an elongated slot forreceiving a portion of the circular blade therethrough, pivot meanssecuring said base plate to said frame adjacent the leading end of theformer for pivoting movement about an axis parallel with the axis ofrotation of said shaft back and forth between a normal position and aninclined position, and adjustment means for securing said base plate insaid positions and in any location therebetween, the improvementcomprising:

a. a first abutment formation on said base plate adjacent the trailingend of said slot;

b. a lower blade guard mounted on said frame for swinging movement backand forth between a closed position and an open position, which lowerblade guard in the closed position thereof cooperates with said upperblade guard to enclose substantially all of the teeth on the blade; and

c. said lower blade guard having a work engaging forward end and asecond abutment formation thereon which is adjacent said forward end,said second abutment formation being brought into abutting engagementwith said first abutment formation upon movement of said lower bladeguard from the closed position thereof toward the open position thereofwhereby the lower blade guard exposes only the blade teeth which extendthrough said slot and beneath said base plate irrespective of thelocation of the base plate between said positions thereof.

2. The improvement according to claim 1 further defined by:

a. said adjustment means including an adjustment arm mounted on saidbase plate adjacent the trailing end of said slot, said first abutmentformation being integral with said arm; and

b. said second abutment formation being integral with said lower bladeguard.

3. The improvement according to claim 1 further defined by a manuallyoperated retracting mechanism for said lower blade guard, said mechanismcomprising:

a. an operating lever pivotally mounted on the side of said fixed bladeguard which is adjacent the power means for rotating said shaft;

b. connecting means engaged with said lever and said lower blade guardfor moving the latter between said positions thereof in response tomovement of said lever; and

c. biasing means engaged with said frame and said lower blade guard forurging the latter toward said closed position thereof.

4. The improvement according to claim 3 wherein said connecting meansincludes a pair of links, one link being secured at one end thereof tosaid lever for movement in unison with the latter, the other link havingone of its ends pivotally connected with the other end of said one linkand having its other end pivotally con- 0

1. In a portable, power operated circular saw of the type having apowered blade mounting shaft and a frame including a fixed blade guardadapted to enclose the teeth on the upper portion of a circular blademounted on said shaft, a base plate having an elongated slot forreceiving a portion of the circular blade therethrough, pivot meanssecuring said base plate to said frame adjaCent the leading end of theformer for pivoting movement about an axis parallel with the axis ofrotation of said shaft back and forth between a normal position and aninclined position, and adjustment means for securing said base plate insaid positions and in any location therebetween, the improvementcomprising: a. a first abutment formation on said base plate adjacentthe trailing end of said slot; b. a lower blade guard mounted on saidframe for swinging movement back and forth between a closed position andan open position, which lower blade guard in the closed position thereofcooperates with said upper blade guard to enclose substantially all ofthe teeth on the blade; and c. said lower blade guard having a workengaging forward end and a second abutment formation thereon which isadjacent said forward end, said second abutment formation being broughtinto abutting engagement with said first abutment formation uponmovement of said lower blade guard from the closed position thereoftoward the open position thereof whereby the lower blade guard exposesonly the blade teeth which extend through said slot and beneath saidbase plate irrespective of the location of the base plate between saidpositions thereof.
 2. The improvement according to claim 1 furtherdefined by: a. said adjustment means including an adjustment arm mountedon said base plate adjacent the trailing end of said slot, said firstabutment formation being integral with said arm; and b. said secondabutment formation being integral with said lower blade guard.
 3. Theimprovement according to claim 1 further defined by a manually operatedretracting mechanism for said lower blade guard, said mechanismcomprising: a. an operating lever pivotally mounted on the side of saidfixed blade guard which is adjacent the power means for rotating saidshaft; b. connecting means engaged with said lever and said lower bladeguard for moving the latter between said positions thereof in responseto movement of said lever; and c. biasing means engaged with said frameand said lower blade guard for urging the latter toward said closedposition thereof.
 4. The improvement according to claim 3 wherein saidconnecting means includes a pair of links, one link being secured at oneend thereof to said lever for movement in unison with the latter, theother link having one of its ends pivotally connected with the other endof said one link and having its other end pivotally connected with saidlower blade guard.
 5. The improvement according to claim 4 wherein saidother link is bent intermediate the ends thereof and has its respectiveends disposed generally above and below said shaft when said lower bladeguard is in said closed position thereof thereby to increase themechanical advantage of said links for facilitating manual operation ofsaid retracting mechanism.